MicroRNA Levels in Cervical Cancer Samples and Relationship with Lesion Grade and HPV Infection.

Background: miR-21, miR-214 and miR-let-7a are three validated and well-known miRNAs. miR-21 is described as an "oncomir" while miR-214 and miR-let-7a are described mainly as tumor suppressors. The role of these miRNAs remains unclear in cervical cancer, an important malignancy among women worldwide and responsible for many deaths every year.

Objective: The objective of this study is to describe the expression profile of miR-21, miR-214 and miR-let-7a in plasma and in cervical scraping from a control group and patients with different grades of cervical lesions and invasive cervical cancer and correlate with HPV infection groups.

Methods: Plasma and cervical scraping were submitted to DNA and RNA extraction. HPV detection and typing were performed by conventional PCR followed by PAGE to amplicons interpretation. The miRNA relative expression in plasma and cervical scraping samples was performed by real time PCR using specific TaqMan probes.

Results: miR-21 (p=0.0277) and miR-214 (p=0.0151) were up-regulated in cervical scraping samples of invasive cervical cancer (ICC) group. However, miR-214 was also up-regulated in the LSIL group (p=0.0062). Both miRNAs were not related to HPV infection. However, miR-let-7a was higher in HPV positive plasma samples (p=0.0433) than in HPV negative plasma samples and the correlation analysis confirmed the association between the levels of this miRNA with the presence of HPV (p=0.0407; r=0.3029), but not with lesion grade (p>0.05).

Conclusion: Our results suggest that miR-21 is related to cervical cancer progression and miR-214 appears to have an ambiguous role in cervical lesions. miR-let-7a may be upregulated at a systemic level in patients with HPV infection.